This invention pertains to the adsorption of SO.sub.2 from gas mixtures and in particular to the use of crosslinked polymers of N-glycidylpiperazine or N-glycidyl polyalkylpiperazines as the adsorbents.
Power plant gas effluents as well as other industrial waste gases contribute to the general environmental air pollution problems extant. One of the six chief air pollutants, SO.sub.2, is a common component of these waste gases. In the past many methods have been used in attempts to reduce SO.sub.2 air pollution by control at its source, but none are being practiced widely in attempts to consistently meet the National Air Quality Standards which call for a maximum of 0.14 parts per million (ppm) of SO.sub.2 for a 24 hour period. Alkaline water scrubbing, ammonia scrubbing, and limestone scrubbing are examples of limited solutions to this problem. Similarly, effective means for removing SO.sub.2 from ambient air, especially within buildings and homes, are not available. Since people spend about 80% of their lives indoors, control of pollutant concentrations that they actually come into contact with represents another approach to solving air pollution problems.
It is an object of this invention to provide a method of SO.sub.2 adsorption from gas mixtures, including ambient indoor and outdoor air, which is selective for SO.sub.2. For example, CO.sub.2 is present in stack gases in much larger quantities than SO.sub.2 and its adsorption is undesirable.
Another object of this invention is to provide an adsorbent with a high capacity for SO.sub.2 adsorption which is chemically stable, water-insoluble and which is readily regenerated.